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LM5143-Q1EVM-2100: Additional parameters on shunt resistor current sensing (not DCR)

Takeshi Sasaki
Expert 4480 points
Part Number: LM5143-Q1EVM-2100

Hi team,

Could you give me comment on following customer questions? They ask parameters related to R15 (49.9Ohm), R16(0Ohm), and C43(33pF) in the EVM. 

Q1. What function does this circuit have?

Q2. What is the case that this circuit should be added? The circuit is always operated? Or The circuit will work for specific operation condition like start-up or large/fast transient response timing etc. 

Q3. Could you tell me how to calculate those parameters?

Best regards,

Takeshi Sasaki

  • +1
    TI__Mastermind 49397 points

    Sasaki-san,

    This is a high-frequency filter for the current sense signal (the components are located close to the IC). It is not mandatory but instead recommended if (a) there are long current sense traces from the shunt to the controller or (b) a noisy PCB layout.

    Please use a layout similar to the EVM, in which case the RC filter should not be required. In any event, the 0 Ohm can be left off and just use a trace from the shunt directly to the VOUT pin of the IC. Route the two current sense signals as a diff pair (side by side or on top of each other on different layers) to minimize any radiated coupling or unwanted noise pickup

    Regards,

    Tim